Billet twister

ABSTRACT

The invention contemplates billet-handling mechanism which accepts heated elongate metal billets of generally square section as they are fed from a furnace to the first of a succession of pinch-roll stands and which, without interrupting or slowing such feed, reorients the entire billet so as present and hold the billet with its section diagonal in a vertical plane. The mechanism for accomplishing this function includes framereference elements, for imparting the requisite 45* or other desired rotational displacement, and floating elements which are actuable between billet-engaging and disengaging positions, at both ends of the rotational-displacement stroke.

United States Patent Paletzki I Feb. 18, 1975 BILLET TWISTER [75] Inventor: Hans Joachim Paletzki,

Georgetown, SC,

[73] Assignee: Georgetown Steel Corp.,

Georgetown, S.C.

[22] Filed: July 24, 1973 [21] Appl. No.: 382,136

[52] US. Cl 214/1 QG, 72/250, 198/283 [51] Int. Cl. 865g 7/00 [58] Field of Search 2l4/l Q, l QG, 1 QA;

198/33 R, 33 AB, 33 AD, 283; 72/250 [56] References Cited UNITED STATES PATENTS 3,487.953 1/1970 Wolf ..2l4/1QG FOREIGN PATENTS OR APPLICATIONS France 198/33 AC Sweden 2l4/I QG Primary ExaminerFrank E. Werner Attorney, Agent, or FirmSandoe, Hopgood &

. Calimafde [57} ABSTRACT The invention contemplates billet-handling mechanism which accepts heated elongate metal billets of generally square section as they are fed from a furnace to the first of a succession of pinch-roll stands and which, without interrupting or slowing such feed, reorients the entire billet so as present and hold the billet with its section diagonal in a vertical plane. The mechanism for accomplishing this function includes frame-reference elements, for imparting the requisite 45 or other desired rotational displacement, and floating elements which are actuable between billetengaging and disengaging positions, at both ends of the rotational-displacement stroke.

26 Claims, 7 Drawing Figures l liill llllll f je a (Z5 26 Q'TfE EF-JTEU FEB I 8 i555 SHEET 1 OF 4 T FZ/P/VACA 5 a r fir m mm 5% Z 0% 7 POZA 5770\0 I W. "M w W PATENT EUFEB 1' M5 SHEET B UF 4 PATEHTEU m1 ems saw u 0F 4 BILLET TWISTER This invention relates to work-handling mechanism, wherein an elongate workpiece such as a steel billet of square section is to be engaged and rotationally dissoftened by heating to rolling temperature. Normally,

such movement is the result of a longitudinal push at the rear end of the billet, on an alignment to produce entry into the first of a succession of roll stands. For those rolling mills which are designed for billet entry on edge, i.e., with the section diagonal generally vertical (the so-called diamond position), it is customary to employ a first twist-inducing roll stand comprising beveled pinch rolls which will impart such rotational twist to the billet as to enable generally the desired verticaldiagonal orientation for entry into the first sectionreducing roll stand.

Billets produced by a rolling mill have characteristic rounded corners, upon which the indicated beveled pinch rolls have little physical effect. But billets produced by continuous casting have corners of characteristically sharp radius, and such sharp corners can be a cause of product damage when handled by beveled pinch rolls, in that damage to one or more corners at one or more longitudinal regions of the billet can cause serious quality damage as the material is progressively reduced in section at successive roll stands.

Aside from the foregoing, further quality damage can be attributed to the fact that some billets are out of square, or for some other reason the diamond position cannot be assured for the full pass of the billet through the first roll stand. For example, in multiple-pass mills, i.e., mills rolling more than one billet, on laterally offset pass alignments through the same roll stands, the billet selected to load an inside pass alignment will have been in closely nested adjacency between other heated billets in the furnace, so that the mass of these adjacent heated billets will present a major impediment to the desired twist erection of the selected billet; in such situations, rotational torque imparted by the beveled pinch-roll station cannot assure a diamond orientation for the full length of the billet, and product quality suffers.

Still further, the normal procedure is to save pinchroll wear by providing means to release pinch-roll engagement with a billet once it has entered the first section-reducing roll stand, and a billet softened by heating may not be rigid enough to assume the rotated (diamond) position for its full length. Thus, parts of the billet not subject to direct pin-roll action may not be in the desired diamond position upon arrival at the first roll stand; again, product quality will suffer.

It is, accordingly, an object of the invention to provide improved billet-orienting means, avoiding the difficulties of past techniques.

It is a specific object to avoid the use of or need for a pinch-roll or guide system for billet twisting in a rolling mill of the character indicated.

It is also an object to provide improved billetorienting mechanism whichvwill assure billet stabilization in diamond position for substantially its entire length.

A specific object is to provide means to automatically engage an on-coming billet and immediately rotate and hold the entire billet in rotated (diamond) position, without impairing or reducing the feeding advance of the billet into the first roll stand.

Another object is to achieve the above objects using twister means which involve a minimum of space allocation in the direction of billet feed.

Still another specific object is to achieve the above objects using means which avoids concentrated action on any corner edges of the billet.

A further specific object is to provide such twister apparatus with the feature that a billet which may have entered and been arrested in the apparatus, and which for some reason may not be usable (e.g. might damage the system of roll stands), may be readily removed, as by a vertical-hoist operation, without first requiring that the forward end be backed longitudinally out of twister engagement.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following description, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, a preferred and an alternate embodiment of the invention:

FIG. 1 is a simplified plan view of the furnace and first roll-stand regions of a two-pass rolling mill to which twister apparatus of the invention has been applied;

FIG. 2 is an enlarged view in elevation of twister apparatus in FIG. 1, the view being taken from the aspect 22 of FIG. 1;

FIG. 3 is a right-end view of FIG. 2, certain centrally located parts being shown in section, on the stepped alignment designated 3-3 in FIG. 2;

FIGS. 4 and 5 are similar, simplified enlarged views in elevation, for the case of the right-hand twister mechanism of FIG. 2, showing various parts relationships in a typical cycle of operation;

FIG. 6 is a diagram schematically indicating control elements of the twister apparatus of FIGS. 1 to 5; and

FIG. 7 is a simplified view similar to FIG. 2 showing a modified twister apparatus in which some of the parts are schematically indicated.

In FIG. 1, the invention is applied to a-furnace 10 serving like heat-softened billets in interlaced sequence to the several pass alignments of a multiple-pass rolling mill, for which the drawing shows only the first 11 of a succession of roll stands, the same being operative to progressively reduce the billet section, as an elongating strand, into wire or rod proportions as required. For the two pass alignments indicated, the legends outside and inside derive from the manner in which billets are readied for ejection from the furnace 10. Twister apparatus 12 of the invention and a gate 13 having a shiftable element 14 are positioned between the exit port of furnace 10 and the first roll stand 11.

In an actual employment of the invention, the billets are of continuously cast steel, 15 meters long, and having a square section which is nominally 10 centimeters on each side. Furnace l0 accommodates such billets, as from an inventory thereof, in side-by-side adjacency, seated square on flat horizontal sides on the furnace floor. Registering forward and rear-end alignments 15-16 are indicated for the supply of billets being heated in the furnace, the same being incrementally advanced (by means not shown) in indexing steps, in the direction of arrow 17. The outermost (i.e., outside) one of these heated billets is designated 18 and is shown being fed by pusher means. 19 through gate 13 and twister 12, being oriented thereby to the diamond position and just about to enter the first roll stand 11, on the outside" pass alignment; pusher 19 will be understood to have billet access through the furnace wall at suitable porting. The next selected billet (designated 20) may be an inside" billet, namely, several billets in and on the inside pass alignment, the same being ejected by pusher means on the inside alignment, as suggested by legend, and with the gate element 14 shifted appropriately to its other position, shown by dashed lines.

Referring now to FIG. 2, the twister apparatus 12 is seen to utilize a single floor-mounted base having longitudinally spaced, transversely extending pairs of upstanding frame plates 26-26, 27-27'; like systems of articulated members serve billet-engaging and twisting functions on the respective pass alignments, the billet 18 on the outside pass alignment being shown in section and in its twisted or diamond position. The de scription of elements serving billet 18 will be understood as typical, duplicates of the same parts being oppositely arranged to serve similar functions for the inside billet 20, the alignment of which is shown merely by phantom outline, because it has yet to be ejected from furnace 10; primed notation of the same reference numbers is used for corresponding twister parts for the inside pass alignment.

Twister mechanism serving the outside billet 18 comprises floating links or jaw member s 28-29 and like end pairs of links 30-31, pivotably interconnected on a succession of pivot centers A-B-C-D-E, of which end pivots A-E alone are frame-referenced. Thus, a pivot pin 32 connects one link 30 to the frame, between plates 26-26', and a second such pin (not shown) will be understood to similarly connect another link 30 to the frame, between plates 27-27 and on the same pivot axis A; in like manner, a pivot pin 33 connects one link 31 to the frame, between plates 26-26, and a second such pin 33 connects another link 31 to the frame, between plates 27-27 and on the pivot axis E. The jaw member 28 is a box-like structure comprising two like side plates of the shape seen in FIG. 2 and secured in spaced relation by hub or yoke means 34, as by weldments suggested at 35. The jaw member 29 is another box-like structure, for which the respective side plates are outside the side plates ofjaw member 28 and inside the inner frame plates 26' 27 and a single pin 36 provides the articulating connection between all side plates of both jaw members 28-29, via a bore in hub means 34. Bolt pins 37 on the pivot axis B establish a first floatingconnection, ofjaw plates 28 to their adjacent links 30; and similar bolt pins 38 on the pivot axis D establish a second floating connection, of jaw plates 29 to their adjacent links 31, the latter being omitted from FIG. 3, for clearer showing.

Each of jaw members 28-29 includes an upwardly projecting offset or dog-leg end by which a workengaging roll 39 (40) is journaled for free rotation. In the case ofjaw member 28, spacer plates 41-42 rigidly connect the spaced jaw plates 28 and establish the axis 43 of rotary support for roll 39; similar structure will be understood to establish the axis 44 of rotary support for the roll 40 on jaw member 29.

To actuate the jaw members between their closed position of work engagement (FIGS. 2 and 5) and their open position (FIG. 4), I employ first double-acting fluid-pressure operated means, shown as a cylinder member 45 gimbal-suspended (at 46) from and between the plates ofjaw member 29 and having a pistondriven connection 47 to a wrist pin 48 carried by the side plates of jaw member 28. To actuate the floatingjaw parts of the mechanism between their square position of and initial engagement with the workpiece (FIGS. 4 and 5) and their diamond" position of workpiece twist orientation (FIG. 2), I employ second double-acting fluid pressure operated means, shown as a cylinder member 50 gimbal-suspended at 51 from and between suitable upstanding frame plates 52 secured to the base 25; an associated piston rod 53 has an end formation 54 pinned at 55 between trunions 56 on a spacer plate or web 57 between the side plates of jaw member 29. Limit of motion for leftward propulsion by cylinder 50, to the diamond-orienting relation shown in FIG. 2, is achieved by two alignments of fixed stops 58-59; stop 58 is a transverse rod extending between frame plates 26 27 to interfere with the lower ends of jaw members 28-29, and stops 59 are fixed abutments for links 30 carried by one or more of the frame plates 26 26' -27' 27. Limit of motion for rightward propulsion by cylinder 50, to the open-jaw square" position of FIG. 4 is established similarly by a fixed rod 60 to interfere with movement of the lower ends of the jaw members, and by fixed abutments 61 for links 30.

For the described parts, a cycle of operation commences with the FIG. 4 relationship, wherein the jaw actuator 45-47 is extended, to hold jaw members 28-29 and their work-engaging rolls 39-40 in retracted position; at the same time, the twist actuator 50-54 is retracted, with parts limited by the described righthand abutments 60-61. A photocell 62 (FIG. 1) focused for optical response on a transverse alignment is operative, upon detection of glowing light from the passing billet 18, to initiate a control sequence whereby jaw actuator 45-47 is retracted, to bring rolls 39-40 into rolling contact with the billet 18 (FIG. 5 situation); as a result of this small motion, all abutment references at 60-61 are relieved and the jaw-member orientation has been referenced to the workpiece engagement. Having engaged the workpiece, means (to be described in connection with FIG. 6) is operative to develop a propulsion stroke by actuator 50-54, thus displacing the jaw-connection axis C to the left, into limiting abutments at 58-59; the parts are then in the FIG. 2 position, with the workpiece 18 twisted into the diamond position. This position is held as long as photocell 62 detects the glowing presence of billet l8, i.e., for the full length of billet passage, at the twister station. The photocell output will drop upon passage of the rear end of billet 18, whereupon both actuator cylinders are simultaneously actuated to return the parts to the FIG. 4 relation, in readiness for approach of the nextsucceeding billet, on the outside" pass alignment.

Various proportions and parts relations are important to ease and efficiency of action in the present mechanism, whereby a billet which weighs in the order of a ton is quickly bodily displaced from the horizontal square" position to the on-edge or diamond position. In the first place, the centers A-B-D are in substantial alignment, along an upward slope in the order of 35 above the horizontal, with links 31 substantially transverse to the initial twist-inducing thrust vector from actuator 50. This means negligible initial displacement of links 31 and a major upward and leftward thrust of jaw member 28, driving pivot B upward along an arc determined by the effective span A-B of links 30. Rotational torque is thus swiftly imparted to the workpiece, primarily through motion of the jaw member 28, so that the workpiece is both lifted and twisted, during substantially one half of the stroke of actuator 50. During the remainder of the stroke, links 3l develop their greatest displacement, but the vertical component of axis D displacement is substantially smaller than that for corresponding displacement of axis B of links 30. Under the circumstances, the billet 18 is not only twisted to the desired angular extent of 45 into the diamond position, but the central axis of the billet is also raised to reduce any tendency for edgedegradation by scuffing on the furnace floor. And by having the dog-leg ends of jaw members 28-29 offset in the same (clockwise) direction from the alignments of their respective pivot axis B-C and C-D, a net component of billet-axis displacement can be achieved in the horizontally rightward direction (direction of arrow 17 in FIG. 1), thus also reducing any tendency for edge-degradation by scuffing against the mass of all billets in the furnace, on the inward side of the billet being twisted. Once in the billet-twisted or diamond position (FIG. 2), the link systems 30-31 assume substantially equal and opposite slopes with respect to the vertical, thereby developing well-stabilized framereferenced support for the moving workpiece.

A simplified electro-pneumatic control system for the described parts appears in FIG. 6, wherein the photocell 62, the jaw actuator cylinder 45 and the twistshifting cylinder 50 will all be recognized. Pneumatic pressure from a suitable source is delivered to a reversing valve 63 for determining whether pressure fluid is to be delivered into one or the other of two outlet lines 64-65. Valve 63 is positioned by a solenoid 66 and the arrangement is such as to normally call for valve 63 to deliver control pressure in line 65, for connection in line 67 to the head end of cylinder 45 and in line 68 to the tail end of cylinder 50; normally therefore, the piston-driven means 47 of cylinder 45 is projected to jawsopen position, and the piston-driven means 53-54 of cylinder 50 is retracted to the square position, all as shown in FIG. 4. While the electrical control of valve 63 may be positive in both directions, i.e., using separate solenoids for each of the actuating directions, the simplified showing in FIG. 6 will be understood to depict a valve 63 and its solenoid 66 wherein spring means (not shown) is relied upon for a stroke which returns the armature to the indicated normal position, wherein the solenoid is not actuated and line 65 is pressured to place and hold the parts in the FIG. 4 position.

As shown, the output of photocell 62, meaning electrical signal response to detected presence of oncoming freshly heated billet 18, is processed in amplifier means 69 to develop an actuating signal to solenoid 66 for as long as billet presence is detected. Valve 63 is thereby shifted to remove control pressure from line 65 and to deliver the same to line 64, having a connection 70 to the tail end of cylinder 45 and a connection 71 to the head end of cylinder 50, the latter connection being via a pilot" valve 72. Pilot valve 72 is carried by the bracket 49 on cylinder 45 and may be simply an onof control device, depending upon whether or not its spring-loaded probe means 73 has been actuated by a tracking element 74 fixed to the piston-driven means of cylinder 45. Forthe position shown in FIG. 6, jaw

members 28-29 are in the open billet-receptive rela- 5 tion, and the tracking element 74 is removed from contact with the pilot valve probe 73; in this condition, valve 72 is in its off position, meaning that pressure fluid is not yet deliverable to the line 71 connection to the head end of cylinder 50. Thus, upon initial detection of billet presence by means 62, the jaws are first actuated with at least the beginning of their closing stroke (actuator 45-47), and when (in the course of this stroke) element 74 is contacted by probe 73 to open valve 72, actuator 50 will develop the requisite billet-twisting stroke. As a practical matter, the described sequence of strokes, which is for the purpose of assuring the jaws will be well on their way to engage the billet before they are called upon to twist the billet, takes place in such rapid succession as to make the strokes appear to be substantially coincident. No such sequence is needed for the return strokes once the billet has cleared the photocell response axis; therefore, the return-stroke control lines 67-68 are both pressurized in parallel.

As already noted, the mechanism 28-29 has its counter-part 28 29 serving billets on the insidepass alignment. Actuators 45'50 for such mechanism 28'-29' appear at the left of the mechanism in FIG. 2, and an additional frame plate 26"-27" (designated by bracket legend in FIG. 2, to illustrate length of such plates) may be provided alongside plates 26-27, for example, to enable staggered interlace of the links 30'-31' with links 30-31, thereby avoiding interference between independent cycles of operation on the inside and outside pass alignments. Since the layout of inside pass twister mechanism is substantially the mirror image of that described in detail for the outside pass alignment, the dog-leg offsets of jaw members 28-29' appear in the direction opposite to that shown for such offsets for jaw members 28-29, as will be understood.

FIG. 7 is a simplified diagram in the style and from the aspect of FIG. 2, to illustrate a modified twister mechanism wherein a single actuator 75 (75') serves the combined purposes of (a) jaw closure upon the billet workpiece and (b) billet orientation to diamond position; the particular diagram also serves to show the square jaws-open relationship for the inside pass mechanism (primed notation) and the diamond jaws-engaged relationship for billet 18 on the outside pass alignment (same part numbers, unprimed notation). Jaw members 28-29, supporting links 30-31 and their frame references are all as described for the system of FIGS. 2 to 5, and therefore the same reference numerals are used as far as possible.

First diagonal corners M-N of a four-bar linkage 76 are pinned to the jaw members 28-29, and the other diagonal corners X-Y of linkage 76 are connected to separate links 77-78 (in the nature of toggle links) driven by the piston-operated means 79 of the single fluid-pressure-operated actuator 75. The four bars 81-82-83-84 of linkage 76 may be duplicates of each other, being of course provided spaced and in duplicate, to assure symmetry of force development with respect to the axis of piston-operated means 79; it will be understood that schematic techniques have been adopted to show link members 77-78 and their connection to means 79, to avoid confusion in the drawing. The structure is completed by an upstanding frame member 85, providing abutment 86 for links 31 and proving gimbal support at 87 for the pneumatic means 75; outboard stop rods 60-60, and the single central stop rod 58, determine limits of swing of the connected lower ends ofjaw members 28-29 and 28 '29', respectively, as in the case of FIGS. 2 to 5.

In operation, the structure of FIG. 6 responds to strokes of actuator 75-79 (75'-79) by first operating via links 78-79 to expand or contract the parallelepiped of the four-bar linkage 76 and by then developing the twist-shifting displacement already described. Specifically, starting with the readiness position illustrated for the primed mechanism (piston-operated means 79 being retracted to hold the parts against frame stops 6086', and holding linkage 76' in its most-nearly square condition), the photocell 62 triggers projection of piston-operated means 79', expanding the diagonal X-Y to its greatest extent (rolls 39-40 firmly engaging billet before twist erection to the diagonal position, namely the position shown for the right-hand unprimed system serving billet 18 in FIG. 7, wherein stop 58 holds the position of the parts and wherein the piston of means 75 will be understood to have attained its forward limit of travel. Once photocell 62 detects full passage of the billet, pneumatic supplies to actuator 75 are reversed, to compel retraction of the piston-operated means until limited by linkage abutments 60-86; in the course of such retraction, links 77-78 collapse the diagonal X-Y to the extent shown at X'-Y', and lug means 88 on the piston rod 79 may interfere with jaw member 29 in the course of such retraction, to assure a positive limit of collapse of diagonal X-Y before bodily displacement of the jaw members 28-29 in the untwisting return stroke direction, in readiness for the next cicle, i.e., for the next detected hot-billet presence.

It will be seen that the described constructions meet all stated objects, with economy of space and motion, providing unrestricted vertical access between the upwardly open jaw system, and requiring such small space in the billet-advance direction as to be usable within existing plant clearances between roll stands or between the first such stand and the gate 13.

While the invention has been described in detail for the preferred and modified forms shown, it will be understood that other modifications may be made without departure from the scope of the invention.

What is claimed is:

l. Mechanism for removably engaging and rotationally translating a workpiece having opposed sides, comprising a frame, two jaw members pivotally connected to each other and having opposed work-engaging means at corresponding locations offset from their pivotal connection, a first linkage member pivotally connecting a first point on said frame to one jaw member at a location intermediate the work-engaging and jawto-jaw pivot locations thereof, a second linkage member pivotally connecting a second point on said frame to the other jaw member at a location intermediate the work-engaging and jaw-to-jaw pivot locations thereof, said frame pivot locations being sufficiently spaced in excess of the spacing between link-to-jaw connections for a work-engaging condition of said jaw members that a limited arcuate displacement of said link members will effect a rotational displacement of work engaged by said work-engaging means, and frame-referenced actuating means connected to at least one of said members for imparting such limited arcuate displacement.

2. Mechanism according to claim 1, including actuating means operatively interconnecting said jaw members at locations offset from their pivotal interconnection for selectively determining the spacing between the work-engaging means of said jaw members.

3. Mechanism according to claim 2, wherein said actuating means comprises fluid-pressure operated means establishing a direct-acting connection between said jaw members.

4. Mechanism according to claim 1, wherein said actuating means comprises two pivotally interconnected links, each of which is connected to a different one of said jaw members, and means including a toggle mechanism operatively connected to the pivotal connection of said links for actuating said jaw members via said links between a work-engaging position and a workreleasing position.

5. Mechanism according to claim 4, wherein said frame-referenced actuating means connection to said toggle mechanism is at a location offset from both said fixed frame points.

6. Mechanism according to claim 4, in which said two interconnected links are links of a four-bar linkage comprising two further such interconnected links, said four-bar linkage being connected to the respective jaw members at a first pair of opposed corners, and said toggle mechanism being connected to the other pair of opposed corners of said four-bar linkage.

7. Mechanism acccording to claim 6, in which the links of said four-bar linkage are of substantially the same effective length.

8. mechanism according to claim 1, in which said frame includes abutment means limiting pivotal rotation of said respective first and second linkage members in their respective jaw-opening directions of movement.

9. Mechanism according to claim 1, in which said frame includes abutment means limiting the swing of said jaw members to substantially the angular limits of movement of their pivotal connection about the axis of the workpiece engaged thereby.

l0. Mechanism according to claim 1, in which the effective lengths of said first and second linkage members are substantially the same.

11. Mechanism according to claim 10, in which the respective linkage-member connections to said jaw members are offset to substantially the same extent from the pivotal connection of said jaw members.

12. Mechanism according to claim 11, in which the said effective lengths are substantially the same as the said offsets.

l3. Mechanism according to claim 12, in which each jaw member includes a dog-leg offset at the workengaging end thereof and in which the work-engaging means of each of said jaw members is oriented in the same direction of dog-leg offset from the alignment of linkage-member connection and of jaw-to-jaw pivotal interconnection.

l4. Mechanism according to claim 1, in which said work-engaging means comprises for each jaw member a cylindrical roll journaled in such jaw member on an axis of rotation which is in the direction of projection of the work-engaging ends of said jaw members.

15. Mechanism for removably engaging and rotationally translating an elongate workpiece having opposed generally flat sides and moving on a longitudinal path through a work-rotating station, comprising a frame at said station, spaced work-engaging rolls, pivotally connected jaw members, each of which rotationally carries one of said rolls, the axis of pivotal connection of said jaw members being offset from and generally parallel to the path of workpiece movement at said station, first means carried by said jaw members for actuating said links between a first or work-engaging position wherein said rolls may engage the opposed flat sides of a workpiece and a second or work-clearing position wherein neither roll can engage either of the opposed flat sides of the workpiece, frame-based means supporting said jaw members for limited rotational displacement, second actuating means referenced to said frame for imparting effective bodily partial rotation to said linked members generally about the axis of movement of a workpiece, and means responsive to entering presence of a workpiece and controlling said first actuating means for movement of said rolls to work-engaging position.

l6. Mechanism according to claim 15, in which said last-defined means is photo-electrically sensitive to presence of a moving workpiece adjacent said jaw members.

17. Mechanism according to claim 15, in which said first actuating means includes means responsive to an actuation thereof and connected to control ensuing actuation of said second actuating means.

18. Mechanism according to claim 17, in which said means responsive to actuation is a trip element carried by a movable part of said first actuating means, and a probe carried by another part of said first'actuating means and positioned in the path of initial actuating displacement of said first actuating means.

19. Mechanism according to claim 15, in which each of said actuating means is fluid-pressure operated.

20. Mechanism according to claim 19, in which sequencing means coacting between said first and second actuating means assures operation of said second actuating means only after initial displacement of said first actuating means in the work-engaging direction.

21. Mechanism for removably engaging and rotationally translating a workpiece having opposed engageable sides, comprising a frame, first and second framepivoted links and first and second floating links pivotally connected to each other and to the respective free ends of said frame-pivoted links, the point of floatinglink interconnection being spaced from the points of frame-pivoted link connection to the respective floating links, work-engaging jaw projections integrally projecting beyond connected locations on said floating links, the spacing between frame-pivot locations substantially exceeding the spacing between floating-link connections to the frame-pivoted links when in workengaged relation, and frame-based actuating means having positioning engagement with one of said links for effecting unitary displacement of said framepivoted links when said floating links are in workengaged relation.

22. Mechanism according to claim 21, in which said frame-pivoted links are of substantially the same effective length and in which said floating links are of substantially the same effective length.

23. Mechanism according to claim 22, in which said frame includes means engageable with some of said links for limiting twisted angular movement of a workpiece held by said jaw projections.

24. Mechanism according to claim 23, in which said limited angular movement is substantially 45 degrees about an axis of the workpiece.

25. Mechanism according to claim 22, in which said frame-pivoted links are oppositely inclined toward each other at their said free ends, the inclinations for one work-engaging position being substantially equal with respect to a base line between frame pivots, whereby said actuating means will necessarily drive the point of frame-based links connection to one jaw through a greater extent of displacement with respect to said base line than the extent of accompanying displacement of the point of frame-based link connection to the other jaw, whereby the workpiece is subjected to (a) a rotational displacement and (b) a net change in offsetting displacement with respect to said base line.

26. Mechanism according to claim 21, in which all said links are of substantially the same effective length between pivotal connection points thereof. 

1. Mechanism for removably engaging and rotationally translating a workpiece having opposed sides, comprising a frame, two jaw members pivotally connected to each other and having opposed work-engaging means at corresponding locations offset from their pivotal connection, a first linkage member pivotally connecting a first point on said frame to one jaw member at a location intermediate the work-engaging and jaw-to-jaw pivot locations thereof, a second linkage member pivotally connecting a second point on said frame to the other jaw member at a location intermediate the work-engaging and jaw-to-jaw pivot locations thereof, said frame pivot locations being sufficiently spaced in excess of the spacing between link-to-jaw connections for a workengaging condition of said jaw members that a limited arcuate displacement of said link members will effect a rotational displacement of work engaged by said work-engaging means, and frame-referenced actuating means connected to at least one of said members for imparting such limited arcuate displacement.
 2. Mechanism according to claim 1, including actuating means operatively interconnecting said jaw members at locations offset from their pivotal interconnection for selectively determining the spacing between the work-engaging means of said jaw members.
 3. Mechanism according to claim 2, wherein said actuating means comprises fluid-pressure operated means establishing a direct-acting connection between said jaw members.
 4. Mechanism according to claim 1, wherein said actuating means comprises two pivotally interconnected links, each of which is connected to a different one of said jaw members, and means including a toggle mechanism operatively connected to the pivotal connection of said links for actuating said jaw members via said links between a work-engaging position and a work-releasing position.
 5. Mechanism according to claim 4, wherein said frame-referenced actuating means connection to said toggle mechanism is at a location offset from both said fixed frame points.
 6. Mechanism according to claim 4, in which said two interconnected links are links of a four-bar linkage comprising two further such interconnected links, said four-bar linkage being connected to the respective jaw members at a first pair of opposed corners, and said toggle mechanism being connected to the other pair of opposed corners of said four-bar linkage.
 7. Mechanism acccording to claim 6, in which the links of said four-bar linkage are of substantially the same effectIve length.
 8. mechanism according to claim 1, in which said frame includes abutment means limiting pivotal rotation of said respective first and second linkage members in their respective jaw-opening directions of movement.
 9. Mechanism according to claim 1, in which said frame includes abutment means limiting the swing of said jaw members to substantially the angular limits of movement of their pivotal connection about the axis of the workpiece engaged thereby.
 10. Mechanism according to claim 1, in which the effective lengths of said first and second linkage members are substantially the same.
 11. Mechanism according to claim 10, in which the respective linkage-member connections to said jaw members are offset to substantially the same extent from the pivotal connection of said jaw members.
 12. Mechanism according to claim 11, in which the said effective lengths are substantially the same as the said offsets.
 13. Mechanism according to claim 12, in which each jaw member includes a dog-leg offset at the work-engaging end thereof and in which the work-engaging means of each of said jaw members is oriented in the same direction of dog-leg offset from the alignment of linkage-member connection and of jaw-to-jaw pivotal interconnection.
 14. Mechanism according to claim 1, in which said work-engaging means comprises for each jaw member a cylindrical roll journaled in such jaw member on an axis of rotation which is in the direction of projection of the work-engaging ends of said jaw members.
 15. Mechanism for removably engaging and rotationally translating an elongate workpiece having opposed generally flat sides and moving on a longitudinal path through a work-rotating station, comprising a frame at said station, spaced work-engaging rolls, pivotally connected jaw members, each of which rotationally carries one of said rolls, the axis of pivotal connection of said jaw members being offset from and generally parallel to the path of workpiece movement at said station, first means carried by said jaw members for actuating said links between a first or work-engaging position wherein said rolls may engage the opposed flat sides of a workpiece and a second or work-clearing position wherein neither roll can engage either of the opposed flat sides of the workpiece, frame-based means supporting said jaw members for limited rotational displacement, second actuating means referenced to said frame for imparting effective bodily partial rotation to said linked members generally about the axis of movement of a workpiece, and means responsive to entering presence of a workpiece and controlling said first actuating means for movement of said rolls to work-engaging position.
 16. Mechanism according to claim 15, in which said last-defined means is photo-electrically sensitive to presence of a moving workpiece adjacent said jaw members.
 17. Mechanism according to claim 15, in which said first actuating means includes means responsive to an actuation thereof and connected to control ensuing actuation of said second actuating means.
 18. Mechanism according to claim 17, in which said means responsive to actuation is a trip element carried by a movable part of said first actuating means, and a probe carried by another part of said first actuating means and positioned in the path of initial actuating displacement of said first actuating means.
 19. Mechanism according to claim 15, in which each of said actuating means is fluid-pressure operated.
 20. Mechanism according to claim 19, in which sequencing means coacting between said first and second actuating means assures operation of said second actuating means only after initial displacement of said first actuating means in the work-engaging direction.
 21. Mechanism for removably engaging and rotationally translating a workpiece having opposed engageable sides, comprising a frame, first and second frame-pivoted links and first and second floating links pivotally connected to each other and to the respective free ends of Said frame-pivoted links, the point of floating-link interconnection being spaced from the points of frame-pivoted link connection to the respective floating links, work-engaging jaw projections integrally projecting beyond connected locations on said floating links, the spacing between frame-pivot locations substantially exceeding the spacing between floating-link connections to the frame-pivoted links when in work-engaged relation, and frame-based actuating means having positioning engagement with one of said links for effecting unitary displacement of said frame-pivoted links when said floating links are in work-engaged relation.
 22. Mechanism according to claim 21, in which said frame-pivoted links are of substantially the same effective length and in which said floating links are of substantially the same effective length.
 23. Mechanism according to claim 22, in which said frame includes means engageable with some of said links for limiting twisted angular movement of a workpiece held by said jaw projections.
 24. Mechanism according to claim 23, in which said limited angular movement is substantially 45 degrees about an axis of the workpiece.
 25. Mechanism according to claim 22, in which said frame-pivoted links are oppositely inclined toward each other at their said free ends, the inclinations for one work-engaging position being substantially equal with respect to a base line between frame pivots, whereby said actuating means will necessarily drive the point of frame-based links connection to one jaw through a greater extent of displacement with respect to said base line than the extent of accompanying displacement of the point of frame-based link connection to the other jaw, whereby the workpiece is subjected to (a) a rotational displacement and (b) a net change in offsetting displacement with respect to said base line.
 26. Mechanism according to claim 21, in which all said links are of substantially the same effective length between pivotal connection points thereof. 